Technological Challenges of Off-Grid Homestead Living, Part 2: Electricity

Reader Contribution by Christopher James Marshall
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Read Part 1 of this series, “Resources”, here.

Electricity — as a modern off-grid homesteader, I want it! Electric power for lighting, computers, radios, phones, pumps, refrigeration, fans, are appropriate and can be integrated into a homestead at relatively low cost from on-site renewable solar, wind, and/or hydro energy sources.

Why is it low cost? Four reasons: 1) the market price for renewable energy components, such as photovoltaic (PV) panels and turbines for wind and water continues to drop; 2) appliances that use electricity are available at second-hand stores; 3) house wiring supplies are obtainable at contractor prices; 4) renewable energy is free to use.

Although non-renewable fossil fuel energy sources can also be used to generate electric power, in the long run, it’s more expensive because the fuel is not free. During the construction phase of my small house, before my solar electric system was setup, I used a gas powered electric generator to run power tools and charge a battery bank to run lights and electronics; then after construction it became a backup to the solar.

Setting up the right size system required me to measure how much power I needed and then make choices about conserving energy and using alternatives to electric power because the initial cost of a renewable energy system increases with how much power you want it to produce, so finding ways to conserve energy is essential. To do this I took power measurements of my appliances by using a hand-held watt-hour meter, e.g. Kill-A-Watt, which gave me a starting point for understanding my power requirements.

My finances afforded the cost of 1,000 watts of PV panels and my homestead site offered 12 hours of sunshine per day in summer and 6 hours per day in winter; with 330 sunny days per year at my site, it works out to a potential of about 3 million watt-hours per year — a little more than half of the 5 million watt-hours that my utility bill reported that I actually used at my townhome before I went off the grid.

Consider the following ‘thumbs-up’ and ‘thumbs-down’ choices and alternatives when sizing your renewable energy system:

The next question—did I want electric power when the sun wasn’t shining? Yes, and therefore a battery bank was needed to store power and then deliver it when the renewable energy source is not producing. Unfortunately, today’s chemical battery technology looses about 25 percent of the power you put into it, so I had to re-size my system accordingly.

Solar and wind electric systems operate intermittently (unlike hydro electric, which can produce electricity continuously) and typically has three other main components: charger controllers, batteries, and inverters. There are four possible off-grid electrical system configurations with these components:

1. No chemical battery. This is ideal if your electrical loads can simply be run with intermittent on-site power like solar or wind and you do not need power when the on-site system is not producing. Note that pumping water into a tank is a type of kinetic battery system and running a refrigerator is a type of thermal battery system.

2. ‘Uninterruptable Power Supply’ (UPS) using intermittent on-site power to charge the chemical battery, with an inverter to draw the power out of the battery and thereby runs the electrical loads continuously.

3. UPS with fossil-fuel engine-generator as the sole power source. Run a battery charger from the generator long enough to charge the battery. Then use an inverter to draw the power out of the battery when the generator is off. Electrical loads can run from the generator or inverter.

4. UPS with on-site solar, wind, or hydro power and a fossil-fuel engine-generator for backup. The generator provides backup power when on-site energy sources are not available. Another example of a fossil fuel backup is a lamp, when electricity is not available, for lighting at night.

Below is the diagram of my off grid electrical system. Everything cost about US$4,000. I installed it myself because I’m an engineer by trade and know about electrical safety and I strongly recommend getting the help of a professional with your system due to the hazards of working with high current and to minimize the chance of damaging the equipment by an incorrect hookup.

Component Diagram of Off Grid Electrical System with On-Site Solar PV and Generator Backup

There are more technical details for off grid, on-site, electrical systems that we don’t have room to cover in this article, but you can find solar, wind, and hydro renewable energy systems, and more, fully explained in my book, Hut-Topia.

In the remaining articles of this series, I’ll go over how I applied old and new technologies for water, food, and heat to make my off-grid homestead work.

Christopher James Marshall is the author of the do-it-yourself small house book Hut-Topia and is a modern-day off-grid mountain man. After weathering recessions and lay-offs every decade since the 70s through the “Great Recession,” he became semi-retired by making plans to live sustainably and then built his 500-square-foot off-grid home. Read all of his MOTHER EARTH NEWS posts here.

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